An important facet of aviation safety is the pilot's situational awareness of the status of the aircraft, including its position, velocity, and external factors such as wind direction and terrain. Toward this end, advances in human factors research have led to dramatic improvements in the display of information to the pilot. Further, advances in visual display technology, such as high quality flat display panels, have enabled the pilot to be presented with information in a visual format that is not possible with traditional dials and gauges.
During operation, the aircraft's heading corresponds to the horizontal component (perpendicular to the local gravity vector) of the direction in which the aircraft is pointing. If the aircraft is flying in wind that has a velocity component at an angle to the heading, the aircraft's direction of flight will change according to a drift angle that is proportional to the speed of the aircraft and the speed of the perpendicular component of the wind velocity. The resulting horizontal direction of the aircraft's motion along the ground is referred to as ground track (hereinafter “track”).
One of the primary flight displays the pilot uses on the flight deck to determine whether the aircraft is on the planned flight path is a horizontal situation indicator (HSI). One function of the HSI is to provide a visualization of the position of the aircraft with respect to a VOR (VHF Omnidirectional Range) radial signal broadcast by a VOR station. The HSI also has a compass card that displays the direction of the aircraft relative to the earth's magnetic field. During flight, the pilot uses the HSI to verify the location of the aircraft against the flight plan.
Most flight plan path procedures are based on ground track, and the flight management system of the aircraft provides navigation information to the HSI that is based on ground track. As such, the information provided to the HSI by the FMS is based on a track-based flight plan. However, at times, air traffic controllers direct the aircraft to fly a heading-based flight plan path. In these situations, pilots must typically mentally convert the track-based indications provided by the HSI into the designated heading-based path, and manually fly the heading-based flight plan path.
Accordingly, it is desirable to provide systems and methods that display symbology for heading-based legs of a flight plan. In addition, it is desirable to provide an HSI with symbology for heading-based legs. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention